[Nook Color General] tonestertm:
Don, I'm glad you posted that, because that's been bugging me for a long time, but I decided to just ignore it and consider the results as "relative". Since everything I'm doing with my cards is on the same test bed, and I tend to run the test multiple times, watching the results along the way (BTW, I think the lowest "intermediate" score I've seen was maybe 2/3 the top speed, I've never had anything as low as 1/2), I know approximately how each card compares to my others. As far as comparison to others in this thread, well, there are so many variables anyway - readers make a HUGE difference - that you just have to take anything with a shaker or two of salt.

So, finally got off (well, actually on) my butt and did some testing I've been thinking about for a while, writing down all the numbers as they showed up. Yep, with pen and paper (the horror!) I should note that I'm still using CDM 3.0.1.

First, I took my CM9 card (SanDisk 16GB Ultra 1) and ran the standard 5x, 50MB, 4kQD32 test a few times. Saw the usual variations and the high score posted as the result.

Next, I ran the exact same test, except I ran the 1x option.

20 times

. I won't bore you with actual numbers, but the results were ridiculously tight, and all on the higher end of the range. If I get really motivated at some point, I'll do some basic statistics and see what they say.

Now, of course, this was only testing the initial 300MB boot partition of the card, so I did the next logical thing ;) and bought a brand stinkin' new card. SanDisk 32GB class 10, UHS1, from Costco -- SDSDQU-032G-AC11A for those keeping score at home.The full test revealed, of course 10x+ serial write speed.

So, I ran the 4kQD32 50MB test again, this time set to 9 iterations. The read number stayed fairly steady, around 4.165 ish, +/- .01. Then, as I watched, the write number started high, at 2.184 (!) and steadily declined to 1.889 (!). I mean, it was a nearly linear drop. Of course, the final result was the 2.184 figure (NEVER seen one this high in my setup before, btw, even other UHS1 cards) Lather, rinse, repeat with nearly identical results, only a tiny bit higher this time, both read and write-- 4.25 and 2.213>1.891.

Next, the 1x iteration, 15 times. Read speeds centered around 4.2ish, but again, the write results were nearly consistent, around 2.2, +/- .01.

Huh....

So, I shrank the test area (first/only partition visible in Windows) from the full 32GB down to 2.8GB, to sort of mimic the "system/data" area of a CM SD install.

Darned if the results weren't virtually identical. Same exact behavior in both 1x and 9x tests.

So, what do we gather?

Well, obviously, there are some technicalities that would be nice to know about how CDM does its multiple iteration testing. Why does the number drop, is this somehow directly testing progressively across the whole memory space (doubt it), or is the wear-leveler in the chip somehow creating the discrepancy/drop? My from-the-hip-no-leg-to-stand-on guess would be that the wear-leveling algorithm/handler is the whole key to the success of the SanDisk where others fail, regardless of whether it's at the root of these results or not.

This card tests ridiculously fast, I'd love to find a meaningful way to benchmark it in use in an SD install.

I started researching for a better test, found something incredibly technical and very comprehensive which I have not yet figured out how to use, and got to wondering... what file size and Queue Depth would best emulate the usage of a Nook Color SD install? Started trying to find that out, and ran out of steam. I'm figuring there's some Android genius (not a genius android, but... you know what I meant!) out there who actually knows something about this without me breaking my brains over it (not that I don't like learning... :) )

There was some other observation I had, but I'm not recalling it atm... If I think of it, I'll edit later.

If I manage to get the time, I'll do some poking around in a Linux environment and see what I can learn. Or... anyone? Bueller?